OPTIMAL BLENDING OF MALTS

A method is discussed for the prediction of the analytical results of blends of malt. The method takes account of the possibility of non-linear interactions between malts when they are mashed by analysing a defined and limited number of blends of the malts as well as the pure malts themselves. A simple mathematical analysis of the experimental points allows the analytical result for any blend to be predicted. Seven analyses are necessary to a blend of three malts: fifteen would be required for a blend of four malts.     

NEW MASHING SYSTEM FOR DETERMINATION OF LABORATORY EXTRACT

The method of preparation of laboratory wort by the Tepral mashing system provides a clear improvement in the evaluation of industrial malts and in the optimization of malting procedures. The equipment required is simple and easy to operate. The use of the method has shown significant differences in terms of both wort viscosity and extract yield between malt from 2-row spring barley (variety Carina) and malt from 2-row winter barley (variety Sonja), produced under identical industrial conditions: the Sonja malt gave fewer good results for finely ground malt than did the Carina malt.     

DETERMINATION OF FATTY ACID HYDROPEROXIDES PRODUCED DURING THE PRODUCTION OF WORT

Linoleic and linolenic acid hydroperoxides in malt, mash, or wort were determined with high sensitivity and high selectivity by the chemiluminescence-high performance liquid chromatography (CL-HPLC) method using isoluminol-microperoxidase solution as a luminescing reagent. The determination limit of this method for both hydroperoxides was 0.1 μM in mash or wort. During the mashing in a laboratory mash bath, the hydroperoxides started to increase just after mashing-in, reached a maximum at 65°C, and then decreased. Though the hydroperoxides were detected in mash just before the lautering in a pilot scale brewing, they disappeared during the lautering and could not be detected during the subsequent stages of wort production. Therefore, it was thought that the mashing process is the most important of the lipid oxidation reactions during wort production. It is also expected that the CL-HPLC method can give useful information on lipid oxidation mechanisms during wort production.     

THE INFLUENCE OF MALT STORAGE ON WORT SEPARATION

With some malts, the readiness with which wort can be separated from a mash improves significantly over a period of about 20 days after kilning. This must be borne in mind when predicting mash-tun performance from laboratory results and also has a bearing on the decision to use very new malt in the brewery in times of high demand.     

Properties of Three Sorghum Cultivars Used for the Production of Bili‐Bili Beverage in Northern Cameroon

The malting characteristics of sorghum malts produced locally in Cameroon for Bili‐Bili brewing were compared with those of malts produced in a laboratory. The analytical values of both malts were similar but the brewing potential of the laboratory malts were marginally better than those of the locally produced malts. Of the three cultivars examined, Madjeru had the lowest levels of β‐amylase, maltose levels and fermentability. The worts of the Madjeru filtered the slowest of the three malts. During malting β‐glucanase developed rapidly and development was temperature‐dependent.     

THE INSTITUTE OF BREWING ANALYSIS COMMITTEE REVISED METHODS OF EXTRACT DETERMINATION

Following a Brewer's Society request to consider a change from a standard Miag Disc Mill setting of 0·5 mm to one of 0·7 mm the Analysis Committee has re-evaluated the determination of hot water extract. It is recommended that from 1st December 1979–1. A Miag Disc Mill setting of 0·7 mm be adopted for grinding malt for the determination of hot water extract. 2. Where an estimate of the fine/coarse grind hot water extract difference is required, mill settings of 0·2 mm and 0·7 mm respectively should be used. The reproducibility of this procedure is adequate to separate malts into classes with high and low values but analytical tolerances cannot be recommended for commercial transactions. Revised methods for setting the Miag Disc Mill and for determining the hot water extract of fine and coarse ground malts are given in Appendix I. It is proposed that all mashes should be made in stainless steel beakers, the use of the standard brewers' mash flask being limited to making the mash to the correct volume at the end of the determination. It is recommended that, from 1st December 1979, the 0·7 mm Miag Disc Mill setting should replace also the 0·5 mm setting in all Recommended Methods for coloured malts, dark malts, roasted barley and unmalted grain. It is further recommended that from 1st December 1979 all specific gravity determinations for laboratory extracts of malt, coloured malt, dark malt, roasted barley, unmalted grain, sugars, syrup, caramel and spent grains should be made at 20°C.     

TECHNOLOGICAL FACTORS OF FLAVOUR STABILITY

The flavour stability of a beer primarily depends on the oxygen content of the bottled beer, but the individual steps of wort production are of similar importance viz:-

• (a) preservation of reducing substances by avoidance of oxygen pick-up during mashing, lautering and wort boiling.
• (b) elimination of substances which are prone to react to flavour active compounds like carbonyls by good mash and wort separation procedures,
• (c) avoidance of an excessive exposure of the wort to heat, to limit the formation of Maillard reaction products and related substances.

Existing brewhouses offer some possibilities to improve the process and thus flavour stability. For analytical control Gas Chromatography and High Performance Liquid Chromatography are excellent tools, even simple analyses help to avoid unwelcome changes in the day to day practice.     

PREDICTION OF WORT COLD BREAK PERFORMANCE OF MALT AND ITS APPLICATIONS

A new test for wort cold break performance of malt was developed, based on laboratory mashing and boiling, followed by adding a range of concentrations of copper finings at different wort pH values. The test predicted successfully brewery wort cold break performance, with malts being ranked on the basis of production of wort cold break which required a low concentration of copper finings for precipitation and flocculation. A relationship between wort pH and the concentration of copper finings required to give an acceptable cold break was established with both brewery and laboratory worts. A strong correlation (r = 0.922, p << 0.01) was found between copper finings concentration and the two variables wort pH and the amount of cold break protein. Differences in brewery cold break performance were explained largely by a difference in wort pH, although other as yet unidentified factors appeared to be involved. Cold break performance of malts was affected by both crop year and protein modification, but not total nitrogen or total soluble nitrogen. A brewing trial is described in which wort pH is increased at the end of boiling, leading to significant improvements in both cold break and isinglass finings performance.     

A SIMPLE AND RAPID TEST FOR ASSESSMENT OF ENDOSPERM PROTEIN MODIFICATION DURING MALTING*

A simple test has been developed for the quantitation of endosperm protein modification in malts. Barley meals or ground malts were extracted with a suitable solvent and the clarified hordein extract diluted into an appropriate precipitant. Of a variety of extractants and precipitants investigated, 1M urea-1% (v/v) mercaptoethanol and 1M sodium chloride were respectively found to be most suitable. Under these conditions a turbid suspension forms; the turbidity of extracts decreased progressively during malting. Turbidity was due to selective precipitation of a specific group of “B” hordeins. In an analysis of nine varieties differing in malting qualities, a significant correlation between the reduction in extract turbidity and cell wall modification (Calcofluor staining) was observed at 48 hours' malting. In addition, for each variety examined, protein modification occurred about one day before carbohydrate modification. Analysis of commercial malts and several samples of selected cultivars from regional trials found good correlations between malt turbidities and percent malt extract and Kolbach index. The test is rapid (10–90 mins) and can be used to screen large numbers of samples; since it is simpler than alpha—amino nitrogen or Kolbach index determination, it may be of use in analysis of malts for protein modification.     

INSTITUTE OF BREWING: ANALYSIS COMMITTEE. RECOMMENDED MILL FOR MALT ANALYSIS

The Miag Disc Mill will become the standard mill for malt analysis on 1st January 1977 and the use of Seck mills for this purpose will be discontinued on 1st January 1978. It is intended that the measurement of coarse/fine difference will eventually supersede the current method of measuring extract. For the interim period it was judged essential to choose a setting of the Disc Mill which ranks malts in the same order in respect of extract values as do the mills currently in use. Following analysis of a range of malts in 3 laboratories a setting of 5 has been chosen.     

THE INFLUENCE OF MASHING CONDITIONS ON WORT AND BEER QUALITY

From a comparison of the performance of ale and lager malts mashed by constant temperature infusion, by temperature programmed infusion, and by decoction procedures it emerges that malt modification and the pattern of kilning are as important in determining the composition of wort as are the mashing conditions. Worts with appropriate levels of amino and total nitrogen and of fermentable sugars may be obtained by selecting lightly-dried well-modified malts and mashing with a constant temperature infusion rather than by using less modified malt in conjunction with more complex mashing programmes. Ale malts yield worts of lower pH which is reflected in a slight reduction in hop utilization. Head retention is improved by the use of undermodified malts but colloidal stability is improved when well-modified malts are used. In the case of well-modified malts a high final curing temperature is not a prerequisite for achieving good colloidal stability in beer.     

Influence of Lauter Turbidity on Wort Composition,Fermentation Performance and Beer Quality in Large‐Scale Trials

Different lauter turbidities (standard 43 EBC vs. turbid 82 EBC on average) were obtained by variation of the lauter procedure, particularly deep raking, in this study. The resulting worts were used for repitching the respective yeast into six subsequent fermentation cycles. The resulting beers were investigated in terms of flavour quality, flavour stability, non‐biological stability and foam stability. Worts gained from turbid lautering showed very similar analytical data compared to the controls (except for a slight but significant increase in linoleic acid). There was an improvement in fermentation performance in terms of a pH decrease and a decrease in extract. The resulting beers were quite similar, and the staling indicators increased slightly, but not significantly, due to turbid lautering. Both types of beer were evaluated on tasting as being of a high flavour quality and neither a professional panel nor a non‐professional (customer) panel was able to distinguish the difference, between standard and turbid lautering, in terms of fresh and forced aged beers. Due to turbid lautering the non‐biological stability appeared to be slightly, but not significantly, decreased while on the other hand the foam stability was significantly improved due to turbid lautering. In conclusion, fermentation performance may be improved by more turbid lautering, and the negative consequences often reported for the resulting beers appear to be overestimated, since the quality parameters of the final beers had not deteriorated significantly.     

Malting for Brewhouse Performance*

In many instances brewhouse performance cannot be predicted from a finished malt specification. This is particularly so for factors such as lautering, yeast performance, filtration and head character. There are two aspects involved in improving the brewing performance of malt. Firstly, an understanding of the malt characteristics affecting particular aspects of the brewing process and secondly an understanding of how the malting process affects or can be controlled to optimise these characteristics and thus their performance. In this work the relationship between barley variety, steeping pattern, malt quality and brewing performance is investigated. Six different barley varieties were micromalted in a Seeger micromalting unit under four different steeping regimes. Sub-samples were taken at intervals during steeping for enzyme analysis and measurement of water distribution. Following steeping, the samples were germinated and kilned using standard micromalting conditions. Finished malts were analysed by standard EBC methods for routine malt quality parameters including apparent attenuation limit. Worts were tested for total β-glucan content, β-glucan molecular weight distribution, filter plugging potential and carbohydrate levels. A sub set of malt samples were then micro-brewed and tested for β-glucan molecular weight (MW) distribution, beer filterability and foam stability.     

EXTRACT AND COLOUR DETERMINATION OF TORREFIED PRODUCTS (WHEAT,BARLEY AND RYE)—COLLABORATIVE TRIAL

A procedure for preparing torrefied products for analysis has been examined and the effects of this procedure on the determination of laboratory extract and colour have been collaboratively tested by the Analysis Committee of the Institute of Brewing. White malts of DP levels 50° and 100° IOB were used as the sources of enzymes in the mixed mash procedure. With these malts r₉₅ and R₉₅ values for extract of the torrefied products ranged from 1.7 to 10.2 and 12.4 to 21.9 resp. on mean extracts ranging from 244 to 270 litre °/kg. The r₉₅ and R₉₅ values for colour ranged from 1.6 to 2.3 and 2.2 to 3.8 resp. on mean colours ranging from 2.7 to 3.5 EBC units.     

COMPARISON OF DIFFERENT MALT ANALYSES

The results of applying three types of analytical mashing procedure—Institute of Brewing, European Brewery Convention, and Tepral systems—to the same malts are examined. Statistical correlations of the results are made. It is concluded that the main difference between the results of the Tepral method and the other two procedures is that the first gives much lower extracts when applied to malts which would be likely to be troublesome in the brewery, and is thus more discriminatory for these. The advantages of including sparging in an analytical method are pointed out.     

THE EFFECT OF INCREASED STEEPING TEMPERATURE ON MALT PROPERTIES

Steeping barley at 30°C instead of 16°C can reduce malting time by 24 hours. The malts produced have normal analytical values but the mashes filter slowly and the malts would be expected to give poor wort separation in a brewery. These run-off problems probably result mainly from starch-protein interactions.     

STUDIES ON COMPARATIVE MALTING CHARACTERISTICS OF SOME TROPICAL CEREALS AND MILLETS

Malts prepared from some of the tropical cereals and millets were evaluated for their suitability in weaning food formulations. Pearl millet and finger millet malts exhibited high α-amylase activity within 2–3 days of germination, while maize, sorghum, wheat and triticale malts showed high enzyme activity after 4–5 days of germination. Malting drastically lowered the paste viscosity of cereal flours especially millet. Finger millet malt had desirable flavour and taste besides high amylase activity. Wheat and triticale malts also had acceptable flavour. Rice malt was bitter and pearl millet malt developed rancid odour and bitterness within a week after preparation.     

COMPARATIVE STUDIES OF KILNED AND FREEZE-DRIED MALTS

The effect of the drying process on malt qualities has been investigated. Green malt samples were dried in a pilot plant kiln, in a brewery kiln or in a pilot plant sublimator (freeze dryer). Some increase of α-amylase activity as dextrinizing power in kilned malts was observed, but at the same time the β-amylase and total diastatic activity decreased as compared with freeze-drying. Modification, amylolytic activity as a whole and the yield of extract were significantly better in the freeze-dried malts, which gave slightly poorer results with regard to colour, turbidity, pH and viscosity of worts.     

THE EFFECTS OF INCREASED STEEPING TEMPERATURES ON ENZYME DEVELOPMENT IN MALT

Malts produced by steeping at 30 °C for a total of 24 h including two air rests, frequently give the same results in routine analyses as do malts produced by steeping at 16°C for longer periods. However, the corresponding worts often filter more slowly under controlled laboratory conditions. The increased steeping temperatures can delay or reduce development of endopeptidase and β-glucan solubitase, but generally have little effect on the activity of α-amylase, carboxypeptidase, or endo-β-glucanase. The problems with wort separation are most probably due to high molecular weight β-glucan and disulphide-linked hordein persisting at the end of malting.